When more is less: the impact of multimorphemic words on learning word meaning

Monomorphemic words have been found to influence category formation, as they encode one general category and thus activate it more than other related categories in the same lexical network. On the other hand, multimorphemic words can encode multiple categories from the same network by the multiple forms they combine. Superordinate categories are encoded by sub-lexical forms (e.g., affixes), while the entire words encode lower categories in the hierarchical structure. In the present study, we asked whether sub-lexical forms influence the learning of the meaning encoded by the entire word they underlie. We used Semitic-like words where sub-lexical forms (syllabic patterns) encode superordinate categories of manner-of-motion, and the entire words encode lower-level categories (moving characters). In our main experiment, a word-learning test showed that a shared syllabic pattern had a negative effect on the learning of the moving characters encoded by the entire word. This effect was revealed mainly in dimensions related to the superordinate category encoded by the pattern. The effect and its direction are beyond the expectations of enhanced category representations suggested in previous literature. We conclude that the effect of word-form is beyond the specific category they encode and can have different directions at different hierarchical levels.